Electrical signals unavoidably include a desired information signal portion and an undesired noise signal portion. The term "signal-to-noise ratio" (SNR) is commonly used to describe the relative strengths of the information and noise signal portions. The performance of electronic equipment generally improves as signal-to-noise ratio is increased. One technique employed to decrease the effects of noise signals and thereby increase SNR is a coring circuit.
A conventional coring circuit removes the center values of a signal, i.e. it provides an output signal only when the input signal is outside a defined range of values. The range of values for which no output signal is provided encompasses a zero or baseline signal value and is usually symmetrical with respect to the baseline signal value. Moreover, in conventional corers, the defined range of values is fixed.
As a result, a conventional coring circuit is effective to remove low level noise signals only when no substantial information signals are present. In other words, noise signals around the baseline level are cored out but noise signals superimposed upon information signals are passed along with the information signals. Moreover, the defined coring range of a conventional coring circuit is not readily changed and so cannot adapt to varying levels of noise signals.